feat: Decode MSI Stream names (#172)

activescott · Nov 3, 2021 · 309f163 · 309f163
1 parent b4db2bb
commit 309f163
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Showing 4 changed files with 113 additions and 2 deletions.
diff --git a/src/LessMsi.Core/OleStorage/OleStorageFile.cs b/src/LessMsi.Core/OleStorage/OleStorageFile.cs
@@ -227,5 +227,58 @@ internal static bool IsCabStream(Stream bits)
 			bits.Seek(0, SeekOrigin.Begin);
 			return cabHeaderBits.SequenceEqual(buffer);
 		}
+
+
+		static char MimeToChar(int val)
+		{
+			if (val < 0)
+			{
+				return (char)('0' + val);
+			}
+			else if (val < (10 + 26))
+			{
+				return (char)('A' + val - 10);
+			}
+			else if (val < (10 + 26 + 26))
+			{
+				return (char)('a' + val - 10 - 26);
+			}
+			else if (val == (10 + 26 + 26))
+			{
+				return '.';
+			}
+			return '_';
+		}
+
+		// Based on ReactOS's / Wine's decode_streamname from msi/table.c
+		public static string DecodeName(string name)
+		{
+			var sb = new StringBuilder(name.Length * 2);
+			for (int n = 0; n < name.Length; ++n)
+			{
+				char ch = name[n];
+				if (ch >= 0x3800 && ch < 0x4800)
+				{
+					int c = ch - 0x3800;
+					sb.Append(MimeToChar(c & 0x3f));
+					sb.Append(MimeToChar((c >> 6) & 0x3f));
+				}
+				else if (ch >= 0x4800 && ch < 0x4840)
+				{
+					sb.Append(MimeToChar(ch - 0x4800));
+				}
+				else if (n == 0 && (ch == 0x4840 || ch == 0x5))
+				{
+					// The code from msi/table.c suggests that a table is always prefixed with 0x4840,
+					// but since we just want to display the name, skip it.
+					// The ENQ char (0x5) is the first char from some other tables, might as well skip that..
+				}
+				else
+				{
+					sb.Append(ch);
+				}
+			}
+			return sb.ToString();
+		}
 	}
-}
+}
diff --git a/src/LessMsi.Gui/Model/StreamInfoView.cs b/src/LessMsi.Gui/Model/StreamInfoView.cs
@@ -30,6 +30,7 @@ namespace LessMsi.Gui.Model
 	internal sealed class StreamInfoView
 	{
 		private readonly string _name;
+		private readonly string _displayName;
 
 		public static StreamInfoView FromStream(System.IO.Packaging.StreamInfo si)
 		{
@@ -39,6 +40,7 @@ public static StreamInfoView FromStream(System.IO.Packaging.StreamInfo si)
 		private StreamInfoView(string name, bool isCabStream)
 		{
 			_name = name;
+			_displayName = OleStorage.OleStorageFile.DecodeName(name);
 			IsCabStream = isCabStream;
 		}
 
@@ -47,11 +49,16 @@ public string Name
 			get { return _name; }
 		}
 
+		public string DisplayName
+		{
+			get { return _displayName; }
+		}
+
 		public bool IsCabStream { get; private set; }
 
 		public string Label
 		{
-			get { return this.IsCabStream ? this.Name + " (CAB)" : this.Name; }
+			get { return this.IsCabStream ? this.DisplayName + " (CAB)" : this.DisplayName; }
 		}
 	}
 }
diff --git a/src/Lessmsi.Tests/LessMsi.Tests.csproj b/src/Lessmsi.Tests/LessMsi.Tests.csproj
@@ -85,6 +85,7 @@
     <Compile Include="MiscTests.cs" />
     <Compile Include="MiscTestsNUnit.cs" />
     <Compile Include="MspTests.cs" />
+    <Compile Include="OleStorageTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="TestBase.cs" />
   </ItemGroup>

diff --git a/src/Lessmsi.Tests/OleStorageTests.cs b/src/Lessmsi.Tests/OleStorageTests.cs
@@ -0,0 +1,50 @@
+using System.Diagnostics;
+using System.Text;
+using Xunit;
+
+namespace LessMsi.Tests
+{
+	public class OleStorageTests: TestBase
+	{
+		[DebuggerHidden]
+		static string FromRawBytes(byte[] data)
+		{
+			// Do not rely on encoding, build it manually!
+			Assert.Equal(0, data.Length % 2);
+			var sb = new StringBuilder(data.Length / 2);
+			for (int n = 0; n < data.Length; n+= 2)
+			{
+				char ch = (char)(data[n] << 8);
+				ch = (char)(ch | data[n + 1]);
+				sb.Append(ch);
+			}
+			return sb.ToString();
+		}
+
+		[Fact]
+		public void TestNameDecode()
+		{
+			// All names extracted from WPF2_32.msp using a c++ scratch project
+			var testdata = new[]
+			{
+				new { Result = "_Columns", Data = new byte[]{0x48, 0x40, 0x3b, 0x3f, 0x43, 0xf2, 0x44, 0x38, 0x45, 0xb1} },	// STGTY_STREAM
+				new { Result = "_Tables", Data = new byte[]{0x48, 0x40, 0x3f, 0x7f, 0x41, 0x64, 0x42, 0x2f, 0x48, 0x36 } },	// STGTY_STREAM
+				new { Result = "T1ToU1", Data = new byte[]{0x00, 0x54, 0x00, 0x31, 0x00, 0x54, 0x00, 0x6f, 0x00, 0x55, 0x00, 0x31 } },	// STGTY_STORAGE
+				new { Result = "#T1ToU1", Data = new byte[]{0x00, 0x23, 0x00, 0x54, 0x00, 0x31, 0x00, 0x54, 0x00, 0x6f, 0x00, 0x55, 0x00, 0x31 } },	// STGTY_STORAGE
+				new { Result = "PCW_CAB_NetFX", Data = new byte[]{0x3b, 0x19, 0x47, 0xe0, 0x3a, 0x8c, 0x47, 0xcb, 0x42, 0x17, 0x3b, 0xf7, 0x48, 0x21 } },	// STGTY_STREAM
+				new { Result = "_StringData", Data = new byte[]{0x48, 0x40, 0x3f, 0x3f, 0x45, 0x77, 0x44, 0x6c, 0x3b, 0x6a, 0x45, 0xe4, 0x48, 0x24 } },	// STGTY_STREAM
+				new { Result = "_StringPool", Data = new byte[]{0x48, 0x40, 0x3f, 0x3f, 0x45, 0x77, 0x44, 0x6c, 0x3e, 0x6a, 0x44, 0xb2, 0x48, 0x2f } },	// STGTY_STREAM
+				new { Result = "MsiPatchMetadata", Data = new byte[]{0x48, 0x40, 0x45, 0x96, 0x3e, 0x6c, 0x45, 0xe4, 0x42, 0xe6, 0x42, 0x16, 0x41, 0x37, 0x41, 0x27, 0x41, 0x37 } },	// STGTY_STREAM
+				new { Result = "MsiPatchSequence", Data = new byte[]{0x48, 0x40, 0x45, 0x96, 0x3e, 0x6c, 0x45, 0xe4, 0x42, 0xe6, 0x42, 0x1c, 0x46, 0x34, 0x44, 0x68, 0x42, 0x26 } },	// STGTY_STREAM
+				new { Result = "DigitalSignature", Data = new byte[]{0x00, 0x05, 0x00, 0x44, 0x00, 0x69, 0x00, 0x67, 0x00, 0x69, 0x00, 0x74, 0x00, 0x61, 0x00, 0x6c, 0x00, 0x53, 0x00, 0x69, 0x00, 0x67, 0x00, 0x6e, 0x00, 0x61, 0x00, 0x74, 0x00, 0x75, 0x00, 0x72, 0x00, 0x65 } },	// STGTY_STREAM
+				new { Result = "SummaryInformation", Data = new byte[]{0x00, 0x05, 0x00, 0x53, 0x00, 0x75, 0x00, 0x6d, 0x00, 0x6d, 0x00, 0x61, 0x00, 0x72, 0x00, 0x79, 0x00, 0x49, 0x00, 0x6e, 0x00, 0x66, 0x00, 0x6f, 0x00, 0x72, 0x00, 0x6d, 0x00, 0x61, 0x00, 0x74, 0x00, 0x69, 0x00, 0x6f, 0x00, 0x6e } },	// STGTY_STREAM
+			};
+
+			foreach(var entry in testdata)
+			{
+				string tmp = FromRawBytes(entry.Data);
+				Assert.Equal(entry.Result, OleStorage.OleStorageFile.DecodeName(tmp));
+			}
+		}
+	}
+}